Call by value -> call by (const) reference.
Use GEOModels in ProjectData only when we build the gui version.
Using QFile instead of QFile*.
Added readFile() to XMLInterface and wrappers for all Xml*Interface classes.
Added first skeleton for xml condition reading interface using boost.
Added empty implementation for BoostXmlCndInterface::write().
Added implementation to read BoundaryCondition.
Correct types for parsing ptree with BOOST_FOREACH.
Reorder #include section.

Boost header must be included before any Qt stuff. It is probably related
to
https://svn.boost.org/trac/boost/ticket/6455 and
https://svn.boost.org/trac/boost/ticket/6131 .
[BoostXmlCndInterface] First version reading parts of boundary conditions using boost.
Removed unused attribute FEMCondition::CondType _type.
Read/process xml tag distribution of fem condition definition.
First version of BoostXmlCndInterface::write().
[BoostXmlCndInterface] Checking if associated geometry exists.